Does anyone know the ration between the Rubicon "Lowest Swash plate position" and the Foreman "First Gear"

My understanding is that the Rubicon "Low" lever position is for the Final drive output after the tranny; A bit like a Hi-Low on a SUV 4x4 Tranfer Case;

What would then be the final drive ratio in the differential for the following:

- Rubicon lowest position on the swass plate + "Low" on the selector;

- Foreman First gear;

I have to pull heavy on hilly terrain and this will help me to decide if I have a risk with the Rubicon;

Thanks,

 

Right off hand , I dont have the ratios, but I know the rubi wont disappoint you. It may not be as mathmaticly low as the foreman first gear, but it has more power, which makes up for that.
Also ive heard the difference between the different d positions on the rubi isnt that noticable, that the ratios arent that different.
Heres a write up on utilities, and they liked the pulling power of the rubi.
http://farmindustrynews.com/mag/farming_atv_rodeo/

 

d1 is auto and its for performance.
it shifts at a higher rpm so the tranny is always on the power band.
d2 is auto also and its for when you want to take it easy and not spin your tires.
but it not for heavy use ortrail riding.
then you have (esp)
manual shift mode.
when im using my rubicon for hauling my trailer i put it in low and shift it manualyand i find on flats im in 2nd, and first for when im going over stuff or up hill.
i had a 03 500 manual arctic cat and the low gears on both quads are very close.
it will do maybe 5mph in low first gear.
if my rubicon wont pull it it will dig it self in to the ground trying.
the rubicon is a great workhorse and just as good a trail quad.
sorry i dont have the ratios for you but i do know that low 1st is about half of 1st high.
hope this helps.

 

The rubicon would always have a lower gear ratio then the foreman or even a quad with a cvt tranny.........atleast in theory (Now alot of this i'll be talking about without taking internal leakage/inefeciancy in the system into account).


Here is why, when the automatic is in neutral the swash plate on the pump is straight up and down, the pump isn't pumping anything. Now i don't know the specs on the hydro pump and motor as for displacement so i'll make up a number. Lets say the motor is a fixed 2cc displacement meaning that it takes 2ci of fluid for it to move 1 revolution. Now the pump is a variable displacement pump, lets say the maximum displacement is 2ci again just to make things simple. Well now if the pump is at full operating capacity its putting out 2ci and the motor being a 2ci displacement will have an output speed on the shaft the same as the input shaft on the pump.

Now if the swash plate is in a "neutral" position the pump isn't moving any fluid and the system is hydraulically locked because fluid isn't moving. So the pump can be putting out a volume of fluid from 0ci/rev to 2ci/rev and inbetween there is infinatly variable. If the pump swashplate angle is moved so the pump is putting out a fluid volume of 1ci/rev and the motor being a displacement of 2ci you get a gear ratio of 2:1. Now you can keep getting smaller if the swashplate angle is set up so the pump is moving .2ci/rev you get a gear ratio of 10:1, and you can keep going till you the pump is no longer moving any fluid at all.

Now here is the twist, all hydraulic systems have a little internal leakage/inefficiancy so your lowest possible gear ratio will be determined by what the inefficiancy is if the pump is moving less fluid then is able to seap around the pistons or else where you won't move. Load has alot to do with this as well. So lets say the the swash plate is set up to move .1ci and your leakage is .09 well your gonna move a little bit but not much because the motor will be turning as if its only getting .01ci of fluid. Now as load increases the internal leakage may increase to the point where the motor won't turn at all. Wear of the internal components determine alot as well.

Its a complecated problem, with no definit answere.

 

DJG 69,

This volume ratio is now clear for me; Thanks

Here is the next problem:

Honda has decided to use a fixed angle swash plate on the pump and a variable angle swash plate on the motor...

This make a pump with 100% fixed volume at all time... with the possible lock in sync. with the motor 1:1 once the motor swash is vertical.... Honda special...!

What I am looking for is what the volume ratio is when the motor swash plat is at max angle; for max torque;

Also, what is the ratio when the drive handle bar is set at "L" (Low) instead of "D" (Drive)

I wonder why Honda don't simply publish those figures like tractor company do;

Have a nice day,

 

thanks Mudblaster,

Sometime, an exemple is worth a lot of formulas;

When you say that the Rubi digs itself in the ground, I presume that it is set in 4x4....

Mud or dirt...?

Thanks agin for the details;

 

Hi Hondabuster,

Its the first time that I get acces to a real life test made for Farm use of ATV;

I have been looking for this type of test for the last month....

This was very informative; If you know of any similar tests on the Rubicon, please advise;

Have a nice day,

 

I just did a google search Honda +rubicon +test


click here

I was surprised when it came up too, as I have never seen that test either.

 

Well to tell you the truth i don't know much about the hondamatic, Most of my knowlege on hydrostatic transmissions comes from diffrent applications and so far most of the ones i've seen have had the variable swashplate on the pump. Again i don't think there is a good answere the only thing i can think of is honda probably wants to keep some of that a secret. One thing i can think of for you to do is hook a tach up to the engine, raise the wheels off the ground stick it in low gear, mark one of the rear tires with some chaulk or some sort of reflective tape, tie the throttle to a certain rpm with a string and count the rear wheel revolutions. Take the rpm of the engine divided by the rear wheel revolution and you get the 1st gear ratio. It won't provide you with an actual amount of torque or hp but knowing the gear ratio will give you a good starting point.

 

Having ridden both a rubicon and a 450S, I can vouch for the S, simply because it will floor you on the hills. The low gearing is better then any ESP or auto tranny that I have ever taken up hills. Still, the Rubi should take care of most hills, simply because the power is a bit better then the S. Really, there isnt a huge diff either way ;-)